Converters are used to generate a current with a periodically changing voltage amplitude from a direct current that is output by an energy storage element. Converters from the prior art use semiconductor elements as switching elements with particularly short switching frequencies.
Furthermore, a technology that is also referred to as a multilevel converter is known from the prior art, in which individual modules each having an energy storage element can be interconnected between different states dynamically during operation of the converter. The modules can be connected in series with one another or in parallel with one another. Furthermore, it is possible to bypass the modules. An output voltage of the converter is thus generated by dynamically connecting the energy storage elements in series and in parallel.
The manufacturing costs of known multilevel converters are brought about, inter alia, by a high number of switching elements. Furthermore, a relatively high number of switching elements also causes a relatively large energy loss.
EP 2 408 081 A1, which is incorporated by reference herein, and EP 2 595 302 A1, which is also incorporated by reference herein, disclose multilevel converters, in which bipolar converter cells are connected to four switching elements and unipolar converter cells are connected to two switching elements. The converter cells can be connected in series or bypassed by switching the switching elements.